Explosive purification



Patented Apr. 8, 1947 EXPLOSIVE PURIFICATION Jerome G. Burtle, Alton, Ill;-, assignor to Olin Industries, Inc., a corporation of Delaware No Drawing. Application October 2, 1944,

Serial No. 555,909

14 Glaims.

This invention relates to explosives and their production and more particularly to their refinement.

This invention has utility when employed in the manufacture of purified cyclotrimethylenetrinitramine, which is commonly known as cyclonite and will be referred to herein as such as well as in the appended claims.

A primary object of the present invention is to produce purified cyclonite from impure or crude cyclonite by an inexpensive process requiring the use of comparatively low cost materials.

Another object is to produce a cyclonite with a lower acid content than the normal or crude cyclonite formed by the usual reactions.

Still another object is to produce a cyclonite with a higher melting point and having improved stability.

Other objects will be apparent in the following specification and claims.

Cyclonite can be prepared in several ways, as, for example, the nitration of hexamethylenetetramine (CeI-I12N4) which is an intermediate formed by the evaporation of an aqueous solution of formaldehyde and ammonia. The production of cyclonite and its properties are described in Chemistry of Powder and Explosives by Davis, vol. II, page 396 (published 1943 by John Wiley & Sons).

It has been discovered that the physical properties of cyclonite are vastly improved by the invention disclosed herein which comprises subjecting crude or unstable cyclonite to a treatment in an aqueous solution of a perborate.

Alkali metal and alkaline earth metal perborates are preferred in the treatment or poach, since these appear to be most effective in purification and improving the stability. For instance, although any suitable alkaline perborate may be employed to advantage, perborates of such metals as sodium or potassium, are preferred. The concentration of perborate in the poaching bath may be varied appreciably without losing the beneficial action and from the standpoint of economy, the bath preferably contains only an amount sufficient to effect the desired purification and stabilization. For instance, a bath containing sodium perborate in amounts in the neighborhood of 0.3% to 1% solution is ordinarily entirely satisfactory. The treating bath is heated to above atmospheric temperature, but at a temperature less than boiling and preferably at 60 to 80 C. The time of treatment may be varied from about two hours to as long .as 12 hours, or longer, depending on the char- 2 acter of the material being amount of purification desired.

By way of example, following is a preferred embodiment of the invention, in which the crude cyclonite having a melting point of about 195 C. to 200 C. is taken directly from the nitration reaction and without previous purification other than water washing. The cyclonite is heated under a reflux condenser in an aqueous solution containing 1% sodium perborate for about six hours at a temperature in the range of 73 C. to 76 C. and preferably not over about 80 C. with the pH of the bath being maintained at about 7.5 to 8.0. During this poaching treatment, the constituents of the bath are subjected to vigorous agitation to suspend the cyclonite and provide for uniformity of treatment. After the six hour period, the cyclonite is separated from the bath in any suitable manner, for instance by filtering, and the cyclonite is thoroughly water washed to remove any residual constituents of the bath and then dried.

Purified cyclonite in a high yield of 97% or more is thus obtained with a low acidity, good stability, melting point and other characteristics satisfactorily meeting the specifications ordinarily required for such material. For instance a product may be obtained having a 10W acidity, a melting point of about 20l.2 C., and a stability of about 3.2, the stability being given in cubic centimeters of gas evolved by five grams of cyclonite held at C., in vacuo, for twenty-four hours.

If desired other reagents may be added to the perborate solution. For instance, in one embodiment favorable results were obtained by poaching 80 grams of cyclonite in a solution of 350 grams of water, 1 gram of sodium perborate, 2500 grams of ammonia and 16 grams of ethyl methyl ketone.

It should be understood that the concentrations, times, temperatures, and other conditions set forth in the above detail embodiments are only by way of illustration and that variations therefrom may be made without departin from the spirit and scope of the invention as define in the appended claims.

Having thus described the invention, what is claimed and desired to secure by Letters Patent 1. The method of purifying cyclonite by subjecting crude cyclonite to a bath containing a perborate.

2. The method of purifying cyclonite by poaching in a bath containing an alkaline perborate.

treated and the 3. The method of purifying cyclomte by poaching in an aqueous bath of an alkali-metal perborate.

4. The method of claim 3 where the perborate content is in the neighborhood 0.3% to 1%- 5. The method of claim 3 where the bath has a temperature in the range of approximately 60 to 80 C. I

6. The method of claim 3 'where the length of poaching time is in the range of about two to twelve hours.

7. The method of treating crude oyclonite including poaching in a bath of sodium perborate.

8. The method of treating crude cyclonite by subjecting the same to a poaching in an aqueous bath of approximately 0.3% to 1% of an alkali metal perborate content for about two to twelve hours at a temperature in the: range of to 80 C.

9. Treating cyclonite by poaching in a bath containing an alkali-metal perborate, washing the treated product and drying the same.

10. Treating oyclonite by subjecting the same to an alkali-metal perborate bath of a character whereby the stability of the cyclonite is improved, washing the treated cyclonite and drying the same.

11. The method of purifying cyclonite comprising heating said cyclonite in an aqueous a1- kaline perborate solution.

12. The method of purifying cyolonite comprising heating said cycionite in an aqueous alkaline inorganic perborate solution.

about 60 13. The method of purifying oyclonite comprising suspending said oyclonite in an aqueous alkali metal perborate solution at elevated temperature.

14. The method of purifyin cyclonite comprising suspending said cyolonite in an aqueous alkaline earth metal perborate solution at elevated temperature.

JEROME G. BURTLE. 

